Benign and malignant blood diseases cause major morbidity and mortality in the US and are rising in prevalence due to the rapid aging of the American population. Effective therapies are rare in part because of an insufficient number of physician-scientists and PhD scientists trained in Hematology research. This proposed Training Program will address this important problem by supporting the training of scientists in basic science or translational research in Hematology. We have designed a Training Program with rigorous research opportunities and close mentoring by faculty. We have assembled an outstanding panel of leading experts in Hematology as Program Faculty to direct fellows in their research endeavors. Fellows will enter the T32 Training Program after clinical training in adult Hematology or directly from the laboratories of Program Faculty through a competitive process. Physician-scientists interested in translational research will have the option of pursuing a Master's Degree in Clinical Epidemiology to acquire skills in the design of clinical trials. Fellow in the T32 Program will receive training in three broad areas of hematology research: hematopoiesis and stem cell biology; thrombosis and vascular biology; and immunology and immunotherapy. Research in the Training Program comprises two years and will be enhanced by didactic lectures, outstanding seminar series and a rich scientific environment. Successful implementation of this Training Program in Translational and Experimental Hematology will lead to new biological insights, novel means of prevention and new therapies for blood disorders by preparing future physician-scientist investigators for careers in research in Hematology.